Influence of bcr-3 PML-RARα transcript on outcome in Acute Promyelocytic Leukemia patients of Kashmir treated with all-trans retinoic acid and/or arsenic tri-oxide.

Aims: Distinct types of PML-RARα hybrid transcripts viz bcr-1, bcr-2 and bcr-3 result from translocation between chromosomes 15 and 17 t(15;17) in Acute Promyelocytic Leukemia patients. We aimed to determine the frequencies of the PML-RARα transcripts and FLT3-ITD mutations in APL patients to evaluate their prognostic implications and also to analyze their impact on disease outcome.

Main Method: RT-PCR and Rq-PCR were adopted for transcript typing and quantitation of PML-RARα transcripts while FLT3-ITD was detected by PCR in APL patients.

Key Findings: PML-RARα bcr-1, bcr-2 and bcr-3 transcripts were found in 26, 3 and 16 cases respectively. 64.4% patients achieved complete remission, 22.2% expired early wherein majority of the cases expressed bcr-3 transcript (p = 0.03). 50% relapse rate was observed in patients with bcr-3 transcripts. Multivariate analysis showed expression of bcr-3 transcript associated with early death (p = 0.027) and increased relapse risk (P = 0.046). Patients expressing bcr-3 hybrid transcript showed lowest OS of 28.0 months (± 5.26) (p = 0.027). FLT3-ITD mutation was detected in 5 (11.1%) patients and presence of these mutations was not associated either with PML-RARα transcripts or with disease outcome.

Significance: bcr-3 transcript has a more lethal outcome and is also associated with frequent relapse risk in APL patients of our region.